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UNITED STATES PATENT OFFICE.

HENRY WV. MERRITT, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR TO HIM- ,SELF, AND BAYAUD 8D STEVENS, OF NEW YORK, N. Y.

PLASTIC COMPOUND FOR WALLS.

SPHCIPIC'A'I'ION forming part of Letters Patent No. 363,408, dated May 24, 1887. Application filed August 7, 1886. Serial No. 2l0,300. (No specimens.)

To all whom it may concern.

Be it known that I, HENRY W. MERRITT, of Somerville, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Plastic Compounds for Walls, &c.', of which the following description is a specification.

Th s invention is an improvement upon certain inventions secured to me by Letters Patent of the United States, No. 322,307, dated July 14, 1885, and N 0.34.1,157, dated May 4, 1886 and its object is to secure a more economlc and better mode and means of making a plastic compound which, when exposed to the air, will set and become extremely hard.

In the practice of my two priorinvcntions, above referred to,I preferably employed as ngredients a highly silicious silicate of magnesia, called 'asbestinefltof chemical character, as setforth in the specification of my ,aDOVG-HZLIIJGCI Letters Patent N 0. 322,307,) in a pulverized condition, quartz-sand, caustic soda or caustic potash, and soluble alkaline sllicateor silicate of soda, mixed with water and dissolvedto give plasticity to the mass.

I have now discovered that bydispensing with the caustic soda or caustic potash and substituting therefor carbonate of lime, prefv erably in the form of chalk or whiting, I produce a much'better plastic compound than by the other methods-the adding of the carbonate of lime aforesaid causing the combination or compound to ,dry more rapidly and harden more thoroughly.

order to make good plaster for walls, cellings, 850., I take ten pounds (10 lbs.) of pulverized asbcstine and four pounds (4' lbs.) of pulverized chalk or whiting. These ingredients I mix with from eighteen. to twentytwo pounds (18 to 22 lbs.) of water, and add thirteen pounds (13 lbs.) of soluble alkaline silicate, (silicate of soda,) thus forming a mass of plastic compound that will fill a pail of ordinary size. With this I incorporate double its bulk, or about two pailfuls, of sand, which if dry would weigh from one hundred and ten to one hundred and fifteen pounds, (110 to 115 lbs.) This mass, when thoroughly inforth.

' termixed, makes a plaster of proper consistency to apply with a trowel in the usual manner, and theplastic compound thus produced will gradually harden when exposed to the air, and finally become stone-like in its character.

I do not restrict myself to the exact proportions of the ingredients above given in the production ofmy improved compound, as these are not absolute, but may be more or less varied within practical limits, such variations depending somewhat upon the density of the soluble alkaline silicate used. I find, however, that the proportions as stated are correct to all intents and purposes.

The highly silicious silicate of magnesia and the soluble alkaline silicate, together with the chalk or whiting, (carbonate of lime,) are the essential constituents of the plastic compound herein described, since the resultant stone-like product is due to their chemical combination when combined with water to form the plastic compound, and sand is combined with them mainly for the purpose of economy in increasing the bulk of plastic material, wherein it is held and bound by the compound formed by the union of the active ingredients. Consequently the proportion of sand can be varied to suit the character of the work for which the compoundis to be used.

The plastic compound, omitting the sand, and formed by the mixture of pulverized silicate of magnesia, pulverized carbonate of lime, water,and soluble silicate of soda, can be used eitheras a cement or as a paint.

I claim- 1. 'A plastic compound consisting of silica and a solid silicate and carbonate of lime, each in pulverized condition, dissolved in water, and a soluble alkaline silicate, the whole being intermixed and incorporated substantially in the manner and for the purposes set 2. A plastic compound consisting of quartzsand, pulverized silicate of magnesia, preferably asbestine and carbonate of lime, and a soluble alkaline silicate, with water to dissolve and give plasticity to the mass.

3. A mixture of pulverized solid silicate, forming a plastic compound suitable for use carbonate of lime, and water, with a proporeither as a cement or a paint. Lion of soluble alkaline silicate, ready for subsequent addition of sand to form aplastic com- HENRY \V. MERRITT. 5 pound, substantially as described.

4. A mixture of pulverized silicate of mag- \Vitnesscs: nesia, carbonate of lime, and water, with a A. GREGORY, proportion of soluble silicate of soda, thus 7 EDW. M. CLARK. 

